Amphiphilic copolymers have the ability to improve membrane flux and antifouling property. Copolymers are also able to induce responsive properties in membranes. It is highly desirable to provide a ...protocol to obtain a library of copolymer modified membranes. Herein, we report a general and convenient approach for the preparation of pH or temperature or simultaneous pH and temperature responsive high flux and low fouling polyvinylidene fluoride (PVDF)/copolymer blend ultrafiltration membranes by conventional phase inversion process. The approach was based on blending PVDF with library of amphiphilic random copolymers containing a common hydrophobic polymer component which is compatible with PVDF. Poly(methyl methacrylate) (PMMA)-co-X copolymers where X=poly(dimethylaminoethyl methacrylate) (PDMA), poly(acrylic acid) (PAA), poly(N-isopropyl acrylamide) (PNIPAM), poly(N,N-dimethyl acrylamide) (PDMAA), poly(N-vinyl pyrrolidone) (PVP), PDMA-co-PNIPAM, PAA-co-PNIPAM and PDMA-co-PDMAA are such versatile blending agents for PVDF, easily synthesized by conventional free radical polymerization. The structural effects of X on the membrane pore radius, porosity, permeate flux, responsive behaviour and fouling resistance ability was systematically studied. The beneficial effect of PMMA as a common polymer component in the amphiphilic copolymers for the preparation of blend membranes is attributed to the compatibility of PMMA with PVDF which lowers the phase separation in casting solutions for further phase inversion and enhances the stability of the copolymers in the membrane matrix owing to the enhancement of interfacial adhesion between copolymer and PVDF. This approach is promising for the preparation of library of PVDF/copolymers blend membranes and screening of membranes thereof for further applications.
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•PMMA-based copolymers are versatile blending agent for PVDF blend membranes.•Library of PVDF/copolymer blend UF membranes are accessible by this simple approach.•PMMA part of the copolymer enhances compatibility/anchoring with PVDF.•Low fouling pH and temperature responsive membranes were easily obtained.•Depending on copolymers, blend membranes exhibited 3–6 times higher permeate flux.
This work explores the scope and limitations of enhancing the poor mechanical properties of diblock copolymers by blending with tapered multiblock copolymers of styrene (S) and isoprene (I), ...P(I‐co‐S)n. Blending of different tapered diblock copolymers (n = 1; Mn = 80 and 240 kg mol−1, 50 wt% polyisoprene (PI) units, lamellar morphologies) affords brittle materials with low elongation at break. An increasing degree of phase separation from (i) miscible P(I‐co‐S)/P(I‐co‐S)n copolymer blends, to (ii) partially miscible and (iii) finally immiscible blends is studied. The effect of miscibility on the mechanical properties is studied for two diblock copolymers (Mn = 80 and 240 kg mol−1, domain spacing of 38 and 77 nm, respectively), blended with a series of multiblock copolymers P(I‐co‐S)n (n = 2–5; domain spacing of 42 to 20 nm) of similar molecular weight. Increasing disparity in the domain spacing results in partially miscible and finally immiscible blends. Immiscibility causes lower elongation at break, albeit superior tensile properties compared to the pure tapered diblock copolymers are maintained. The study shows that the addition of a minor fraction of multiblock copolymers to diblock copolymers is a versatile method toward improved mechanical properties, while retaining an ordered nanophase‐separated morphology.
The poor mechanical properties of diblock copolymers can be enhanced by blending with tapered multiblock copolymers. Results demonstrate enhanced elastic response and toughness introduced by the addition of a limited amount of a multiblock copolymer. These results may guide future industrial processes based on the synthesis of thermoplastic elastomers as blends of tapered diblock and multiblock copolymers with predictably mechanical properties.
The research team has developed new plastic scintillators in the form of microspheres, called PSm, by combining styrene, 9-vinylcarbazole (VK), and 4-vinylbenzyl chloride (VBC). The primary objective ...of this study was to explore the feasibility of incorporating the fluorescent solute (VK) into the polymer structure to prevent its leaching out when PSm are utilized in liquid flow through detection systems or organic solvents. The secondary aim was to examine the impact of adding the chlorine functional group to the scintillation polymer, with the intention of replacing it with an extractant in the future to create covalently linked PSresins.
The findings of the study reveal that the homopolymer of polyvinylcarbazole (PVK) performs poorly while used as a unitary scintillator system for plastic scintillation measurements. However, the incorporation of monomers in the form of copolymers with styrene has a more significant impact on scintillation properties compared to the mixture of homopolymers. In the case of 9-vinylcarbazole (VK), its presence at a weight proportion of 10% leads to an increase in scintillation efficiencies, although it is still inferior to the classical PS. Conversely, the situation is different for 4-vinylbenzyl chloride (VBC), where the chlorine in the copolymer results in higher quenching, and the polymer is also less resistant to organic solvents due to the formation of short polymer chains. For VBC, the mixture of polymers yields better results and enables the production of covalently linked PSresins.
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•Vinylcarbazole may act as fluor for scintillation if copolymerized with styrene in a 10% proportion.•P(ST-VBC) scintillating copolymers are highly affected by quenching.•P(ST-VBC) copolymers are structurally weak and become dissolve in methanol.•Cl-moiety can be included in scintillators by mixing PS and PVBC.
While reactive compatibilization has been widely used, both the compatibilization efficiency and the varieties still need further enhancements. Herein, we demonstrated a novel “Dual-reactive ...compatibilization” strategy using a compatibilizer containing bifunctional groups. It was shown that the compatibilizer containing two types of reactive groups shows higher compatibilization efficiency as compared with traditional compatibilizer with only one type of reactive groups. Specifically, a series of poly(styrene-co-(glycidyl methacrylate)-co-(maleic anhydride)) ternary copolymers (SGM) containing both reactive epoxide groups and maleic anhydride groups were synthesized and then incorporated into the immiscible poly(amide 11)/poly(l-lactic acid) (PA11/PLLA) blend. The terminal amino groups of PA11 are ready to react with the maleic anhydride groups of the SGM while the carboxyl groups of PLLA react with the epoxide groups of SGM. Double-grafted copolymers with both PA11 and PLLA chains were in-situ formed and located along the PA11-PLLA interface, in which the grafted PLLA chains were buried in PLLA phase while the grafted PA11 chains were immersed in PA11 phase. Thus the compatibility of PA11/PLLA was significantly improved. In addition, the effect of SGM structure on compatibilization efficiency was investigated. The PA11/PLLA (50/50) blends with 3 wt % specific compatibilizer (P(S93-G5-M2)) show the elongation at break and tensile strength of 411% and 57.9 MPa, respectively, the highest values reported so far for the blends. This work provides a new strategy to compatibilize immiscible polymer blends (especially the blends of engineering plastics containing reactive groups). Moreover, the novel bifunctional reactive compatibilizers are also ready for large-scale industrial applications.
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•Compatibilizers containing two types of reactive groups (SGM) were synthesized.•The compatibilized PA11/PLLA blends exhibited the excellent ductility, super impact strength and high tensile strength.•Effect of SGM structures on compatibilization of PA11/PLLA blends were investigated.
In this work, the authors report a novel single‐step, one‐pot process for the synthesis of self‐assembled nanoparticles using a polymerization‐induced self‐assembly (PISA) mechanism. In contrast to ...conventional approaches employing a pre‐formed macromolecular stabilizer, the disparate reactivities between two monomers, oligo(ethylene glycol) methyl ether methacrylate (OEGMA) and diacetone acrylamide (DAAm), are exploited instead to synthesize a gradient copolymer directly in aqueous solution. Due to the hydrophobicity of poly(DAAm), these gradient copolymers can self‐assemble in situ to form spheres and worms stabilized by the OEGMA residues. A surprisingly broad range of parameters are identified in which the worm morphology can be stabilized, which is highlighted by significant gelation of the reaction mixture in situ. This single‐step gradient copolymerization approach to PISA is more efficient than conventional two‐step syntheses. These results demonstrate improved reproducibility owing to the production of self‐assembled nanoparticles directly in a one‐pot and single‐step synthesis.
A novel single‐step, one‐pot strategy for polymerization‐induced self‐assembly is presented. This approach exploits the disparate reactivities between two monomers, oligo(ethylene glycol) methyl ether methacrylate (OEGMA) and diacetone acrylamide (DAAm). Due to the hydrophobicity of poly(DAAm), these gradient copolymers self‐assemble in situ to form nanoparticles of different morphologies such as spheres and worms directly in a single‐step reaction.
Reactive compatibilization is an effective strategy to improve compatibility of incompatible polymer blends. However, the strategy is usually limited to the polymer blends that one of the components ...contains reactive groups. In this work, we have succeeded in the reactive compatibilization of the immiscible poly(vinylidene fluoride)/low density polyethylene (PVDF/LDPE) blends of which both components do not contain the reactive groups. We simultaneously incorporated the carboxylic acid terminated poly(methyl methacrylate) (PMMA) oligomer (PMMA−COOH) and ethylene-glycidyl methacrylate copolymer (EGMA) into the PVDF/LDPE blend. The ring-opening reactions of the carboxylic acid groups of PMMA oligomer and epoxide groups on the EGMA main chains happen during the melt blending and the in-situ formed EGMA-g-PMMA graft copolymers enhance the compatibility of PVDF/LDPE blends significantly. The reactive compatibilized PVDF/LDPE blends have the elongation at break and fracture strength of 507% and 40.2 MPa, respectively, as compared with the 11% and 25.6 MPa of the uncompatibilization blends. Moreover, the architecture effects of the in-situ formed EGMA-g-PMMA by varying PMMA-COOH oligomer loadings, PMMA-COOH molecular weight and the processing time on the compatibilization efficiency have been investigated. It was found that compatibilizing efficiency increases with increasing the grafted density, the length of the side chain and the degree of reaction. This one-pot strategy with the in-situ formed graft compatibilizers in incompatible blends paves new possibility for unreactive blends by reactive compatibilization.
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•High performance PVDF/LDPE blends were prepared.•PMMA side chains were grafted onto the EGMA main chains by the ring-opening reactions.•The molecular architecture of the in-situ formed PMMA-g-EGMA showed drastic effects on the compatibilization.
Ultrasmall silica‐based nanoparticles (SNPs) are attractive for application in many fields, but existing synthetic approaches show limited control over the size and morphology of these SNPs. This ...study describes a general single copolymer chain‐mediated strategy for the scalable synthesis of highly monodispersed symmetric and asymmetric SNPs with sub‐50 nm diameter. Random copolymers of poly(acrylic acid‐r‐styrene) intramolecularly collapse into ultrasmall single‐chain nanoparticles and serve as seeds to template the hydrolysis of silica precursors to produce uniform SNPs. It is shown in experiments and simulations that the composition and random architecture of the copolymers are crucial to the formation of ultrasmall seeds and the uniform deposition of silica. Furthermore, tailoring the architecture of copolymers can be used to produce ultrasmall asymmetric Janus‐like and dumbbell‐like SNPs with well‐defined polymer and silica domains. This study paves a new route to the scalable production of ultrasmall SNPs with tailored morphologies.
Random or block‐random copolymers intramolecularly collapse into ultrasmall single‐chain nanoparticles and serve as seeds to template the hydrolysis of silica precursors to produce highly monodispersed ultrasmall silica‐based nanoparticles (SNPs) or asymmetric polymer/silica SNPs with different morphologies (e.g., Janus‐like and dumbbell‐like structures) in an organic solvent.
The switchable catalysis using a commercial salenMn catalyst was firstly developed and applied in the one‐pot selective copolymerization from anhydrides, epoxides, CO2 and ϵ‐caprolactone (ϵ‐CL) ...mixtures for the precise synthesis of AB, ABA and novel ABC block copolymers. The observed unique double switch process comprising three different polymerization cycles was rationalized by theoretical calculations. Surprisingly, the first block turned out to be an efficient macromolecular initiator for the consecutive introduction of carbonate linkages into copolymers, albeit with dominant cyclization with the catalyst alone. Further, through the selective reaction on different epoxides, the switchable copolymerization of up to five monomers was achieved yielding well‐defined multi‐block copolymers with structural diversity and functionality.
The precise synthesis of well‐defined block copolymers with molecular complexity by simple techniques has always been a meaningful but rarely achieved task. Here, a commercial switchable catalysis is reported comprising a delicate “double switch” process. This unique switch can be applied up to pentacomponent mixtures to prepare sequence‐controlled AB, ABA, and ABC copolymers.
A series of proton exchange membranes were prepared from poly(ether sulfone) multi-block copolymers grafted with densely pendent sulfoalkoxyl side chains for fuel cell applications. Each polymers ...contains four pendent sulfonic acids per unit. The chemical structures were confirmed by 1H NMR and FTIR spectroscopy, providing evidence of complete methoxy conversion and sulfobutylation. The introduction of densely grafted flexible pendent side chains to the block structure was effective to enhance phase separation and thus form broader hydrophilic channels. These membranes displayed considerably improved proton conductivities especially at low RH conditions. Furthermore, these membranes also showed promising fuel cell performance both at 20% and 80% RH conditions. In comparison to Nafion 212 membranes, the present membranes displayed enhanced swelling behavior, mechanical strength, proton conductivity, and fuel cell performance, demonstrating that they can be an alternative PEM to perfluorosulfonic acid polymers.
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•Highly-conducting poly(ether sulfone) multi-block copolymers have been developed.•The multiblock copolymers grafted with densely pendent sulfoalkoxyl side chains.•Densely grafted side chains and block structure enhanced phase separation.•Prepared membranes showed promising fuel cell performance.
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